4 Molecular Compounds – IntroNo ionsCharges will not balanceComposed of two nonmetalsSharing of electronsCovalent bondingNaming is based on prefixes

5 Nomenclature of Binary CompoundsIf both elements are nonmetals we must use prefixes.The 1st element only gets a prefix if it is greater than 1.2nd element always gets a prefix and change the ending to -ide

6 Nomenclature of Binary CompoundsExample of a molecular comp:CO2COCCl4

8 Naming Acids An acid is any compound that starts with a hydrogenWhen naming an acid:1st locate the anion (- charge)

9 Acid Nomenclature If the anion in the acid ends in –ide (not PI)change the ending to -ic acid and add the prefix hydro-hydro________ic acidHCl

10 Acid Nomenclature If the anion in the acid ends in –ate (all PI’s)change the ending to -ic acid.___________ic acidHClO3

11 Acid Nomenclature If the anion in the acid ends in –ite (all PI’s)change the ending to -ous acid._________ous acidHClO2

12 Acids – Finishing Up If you have the name and need to find the formulaExample: Acetic AcidCross off the –ic and add at –ateAcetate! = C2H3O2-Finish by adding the correct # of H’s (1 for every negative)HC2H3O2 is acetic acid 

14 Covalent Bonding Covalent bond – atoms share electrons.There are several electrostatic interactions in these bonds:Attractions between electrons and nucleiRepulsions between electronsRepulsions between nuclei

15 Lewis Dot Structures ONLY Valence (outer) electrons are involved.Lewis dot structures can be drawn for:atomsmoleculesLewis dot structures show structure of a molecule, and help predict shape.

16 Steps to Writing Lewis StructuresFind the sum of valence electrons of all atoms in the polyatomic ion or molecule.PCl3(7) = 26

17 Writing Lewis StructuresArrange element symbols to show how atoms are connected – show electrons as dots.Draw in the valence electrons of each of the atomsKeep track of the electrons:

18 Writing Lewis StructuresConnect the lines to form single bonds.1 line = 2 electronsKeep track of the electrons:

19 Writing Lewis StructuresFinish by checking for octets.Hydrogen only needs 2 electrons to be happyKeep track of the electrons:

20 Writing Lewis StructuresIf the central atom does not have an octet……form multiple bonds until it does. Example: HCN

21 Exceptions!Boron and Aluminum are okay with only 6 e- around themBF3

22 Exceptions If the Lewis Dot Structure you are drawing is an ion:Use [] and specify the chargeAdd or subtract electronsPositive charges take away electronsNegative charges add electronsExample: Br-